Pitching coach Dan Warthen on Sunday morning insisted Johan Santana is progressing well from September shoulder surgery, and suggested the only thing that might prevent Santana from throwing today is the celebration of the left-hander's 32nd birthday.

Santana has been throwing on flat ground. GM Sandy Alderson has suggested May 1 is a realistic target for Santana to step on a mound.

The progress "has been great," Warthen said. "We've been actually sneaking him back a couple of extra feet each time without him really knowing it, but I think he does know it. The arm is working in great position -- he's getting it up. He's missed a day here and there, but he's gone back-to-back because he missed [on] his wife's birthday. We gave him an extra day there. So everything is going right on target, maybe a little bit ahead."

In any rehab, it may not be a smooth progression of recovery. So has Santana had any setbacks? Warthen insisted nothing noteworthy, not since a couple of week delay in beginning to toss a baseball in January.

"Ever since then he has not missed any throwing time," Warthen said. "... He's right on time, if not maybe a step or two ahead of that."

According to Warthen, Santana is making 30 throws at 45 feet. He then goes to 70 feet for 40 throws.

At the start of camp, he was making 25 throws at 40 feet, waiting for a few moments, then making another 25 throws at that distance.

"We're moving back," Warthen said.

Privately, people close to Santana accept he might be a shell of himself in the second half, assuming he returns.